Powered screwdrivers are much more efficient than manual screwdrivers for driving screws and bolts. However, without exercising great care, powered screwdrivers can over-tighten or over-rotate screws or bolts. In some critical applications, such as in surgical applications, users may drive screws manually to avoid over tightening or to orient a driven screw or bolt at a desired rotational position. In these instances, a user may drive a screw with a powered driver until the screw begins to approach the critical location. Then, in order to reduce the chance of over-tightening or over-rotating, the user may set aside the powered driver and manually tighten the screw with a separate ratchet or a manual screwdriver.
Ratchets are more efficient than manual screwdrivers for tightening screws or bolts because they prevent rotation in the driving direction and provide continuous freewheel rotation in the other. Accordingly, ratchets are often preferred over manual screwdrivers in surgical applications. Conventional ratchets use mechanical assemblies between the handle of a driving tool and the hardware being driven. For example, conventional mechanical ratchet assemblies include gear systems, high friction surfaces with pawls, sprockets with teeth and pawls, or sprags to mechanically limit rotation in one direction.
These conventional ratchets require large mechanical assemblies that increase both the size of the overall tool and increase the overall weight. For example, ratchet housings must be sized to accommodate the mechanical ratchetings systems. In addition, these mechanical assemblies add mass to the ratchet and subsequently, add additional inertia to the rotating components of the tool. Larger, heavier systems may increase operator fatigue and/or operator injury, potentially resulting in less effective screw targeting. This may affect the patient's surgical outcome.
The device and methods disclosed herein overcome one or more of the shortcomings discussed above and/or in the prior art.